Re: [PATCH][RESEND] tracing/ftrace: Remove unused code in sched_switch tracer

From: Frédéric Weisbecker
Date: Fri Oct 31 2008 - 08:15:56 EST


2008/10/31 Frederic Weisbecker <fweisbec@xxxxxxxxx>:
> When init_sched_switch_trace() is called, it has no reason to start
> the sched tracer if the sched_ref is not zero.
>
> _ If this is non-zero, the tracer is already used, but we can register it
> to the tracing engine. There is already a security which avoid the tracer
> probes not to be resgistered twice.
>
> _ If this is zero, this block will not be used.
>
> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
> ---
> kernel/trace/trace_sched_switch.c | 8 --------
> 1 files changed, 0 insertions(+), 8 deletions(-)
> diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
> index 59de514..96620c7 100644
> --- a/kernel/trace/trace_sched_switch.c
> +++ b/kernel/trace/trace_sched_switch.c
> @@ -203,14 +203,6 @@ static struct tracer sched_switch_trace __read_mostly =
>
> __init static int init_sched_switch_trace(void)
> {
> - int ret = 0;
> -
> - if (atomic_read(&sched_ref))
> - ret = tracing_sched_register();
> - if (ret) {
> - pr_info("error registering scheduler trace\n");
> - return ret;
> - }
> return register_tracer(&sched_switch_trace);
> }
> device_initcall(init_sched_switch_trace);
>

(depends on tracing/ftrace: Fix a race condition in sched_switch tracer)
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